低温弱光对抗氧化酶活性的影响(海南大学侯伟)

Effectsofsub-optimaltemperaturesandlowlightintensityonthegrowthandanti-oxidantenzymeactivitiesinwatermelonseedlingsInDecember2014HouWeiHainanUniversityLayout

BackgroundExperimentalProgramExperimentalResultsConclusions0℃10℃

Optimum

T℃

High

T℃

Freeze

injury

ChillingSub-optimalTBackgroundManyofstudiesfocusedonExcessirradiancealoneorincombinationwithchillingcancauseoxidativestress.Excessofirradiancewithhightemperaturescancausephotooxidativestress.

EffectofchillingorlowlightstressonplantPhysiologyRaretestavailablefortheeffectofsub-optimaltemperaturesandlowlightintensityThestudiesofgrowthandanti-oxidantenzymeactivitiesinwatermelonseedlingsarelimitedExperimentalProgramWatermelon

ZaoJia8424wasusedinthisexperiment,Theseedsweresown

inpotsandthenmovedtoagreenhouseundernaturalPPFD300-380attemperaturesof32(day)/22°C(night).Seedlingsatthethree-leafstageweresubjectedtolowlightand/orsub-optimaltemperaturesinartificialclimateboxesPlantsweredividedintofourgroups.Onegroupwaskeptundernormaltemperaturesof25/18°C,PPFDof250asthecontrol.Thetemperaturesstressgroupwassubjectedto15/10°C.ThelightstressgroupwassubjectedtoaPPFDof100.Thetemperature+lightstressgroupwassubjectedtoatemperatureof15/10°C,andalightconditionatPPFDof100.WedeterminatemorphologyofplantsincludingHypocotyllengths,Stemdiameter,andLeafareasafter7dand14doftreatment,andanti-oxidantenzymeactivities,alondialaehyde(MDA),prolineandsolublesugarsweremeasuredafter3,6,9,12dofstresstreatment.Tab1.ThecombinedtreatmentoflowlightandchillingtemperatureTreatment

LightintensityTemperatureControl25025/18°Csub-optimaltemperatures25015/10°CLowlight10025/18°Ctemperature+light10015/10°CResultsGrowthresponsesSub-optimaltemperaturescausedaslightinhibitoryeffectongrowthofhypocotylsandleaves,butwithlowlightconditionssignificantlyinhibitedhypocotylelongation,leafexpansion,andstemdiametergrowth.Thatmightbeassociatedwiththereductioninphotosyntheticcapacityanddecreasedratesofenzymaticreactionscausedbybothlowtemperaturesandlowlight.Lowlightintensitysignificantlyinhibitedstemdiametergrowthbutpromotedhypocotylelongationandleafexpansionmayindicateplantsexploitthelimitinglightinamoreefficientwaybyincreasinghypocotylslengthsandleaf

area.DiscussionⅠMitochondrion,ChloroplastPeroxisomeChangesintheactivitiesofanti-oxidantenzymesMDAMDAMDAPro,SugarMDAMDAMDAMDAMDAMDAMDAMDAMDAMDAMDAMDAMDAMDAMDAMDAMDAPro,SugarPro,SugarChangesintheactivitiesofanti-oxidantenzymes[Controlconditions(■),Sub-optimaltemperatures(●),Lowlight(▲),orSub-optimaltemperaturesinlowlight(◆)]Sub-optimaltemperaturesSub-optimaltemperaturesAnti-oxidantenzymeactivityismoresensitivetolowtemperaturescomparedwithlowlight,lowtemperaturesconditionsactivatedanti-oxidantenzymeactivityandprotectedcellmembranefromlipidperoxidation.Inaddition,combinedlowtemperatureandlowlightstressreducedtheactivitiesofSODandPODrelativetosub-optimaltemperaturesstress.DiscussionⅡChangesinthemalondialdehyde(MDA)concentrationSub-optimaltemperaturescombinedwithlowlighthadlittleeffectonMDAconcentrationcomparedtosub-optimaltemperaturesalone,indicatingthatlowerlevellipidmembraneperoxidationoccurredandlowlightappearstopromoteadaptabilityandtolerancetolowtemperaturesDiscussionⅢChangesintheprolineandsolublesugarsconcentrationRelativelysmallincreaseofprolineandsolublesugarswereobservedasaresultofinteractiveeffectsofsub-optimaltemperaturesandlowlightcomparedwithsub-optimaltemperaturesalone.Thismightbeattributedtorelativelystableosmoticpressureandcellularstructuresinplants.

DiscussionⅣWeconcludethatcombinedstressofsub-optimaltemperaturesandlowlightintensityhadastronger

inhibitoryeffectongrowthofhypocotylsandleavescomparedwithlowtemperaturesaloneorlowlightalone.Incontrast,theeffectsofsub-optimaltemperaturesonanti-oxidantenzymesactivitiesandtissueconcentrationofMDA,prolineandsolublesugarsweremoresignificantthansub-optimaltemperaturespluslowlight.Lowlightintensityhadawea